Dobby mechanism for looms

ABSTRACT

Dobby having cams of a varying ratio for looms, in combination comprising a rotary cam carrying drum, interchangeably carrying a plurality of cams, each of which through a cam follower means and a suitable spring return lever system operating a corresponding heddle carrying frame in the loom. The cams may be either disc cams or chain cams at the same time winding up on a second idle drum which can be moved to or away from the first drum to accomodate chain cams of a different length for operating said chain cams.

United States Patent Menegatto 154] DOBBY MECHANISM FOR LOOMS [72] Inventor: Carlo Menegatto, Corso Sicilia 108/10, Milan, Italy [22] Filed: I May 18,1970

[21] Appl. No.: 38,380 [30] Foreign Application Priority Data June 7, 1969 Italy 17880 N69 [52] US. Cl. ..139/78, 139/57, 139/79 [51] Int. Cl ..D03c 5/00, D03c 13/00 [58] Field of Search ..109/78, 79, 57, 55, 329, 67, 109/58, 334

[56] References Cited UNITED STATES PATENTS 2,263,678 11/1941 Cosman .;....139/79 561,933 6/1896 Beaumont et a1 ..l39/329 X 127,055 5/1872 Hillsley ..139/78 132,279 10/1872 Gminder 1 39/78 3,603,351 9/1971 Piazzolla ..'...l39/79 FOREIGN PATENTS OR APPLICATIONS.

Great Britain ..139/78 1 Oct. 3, 1972 3,491 Great Britain 139/78 12,950 1895 1 Great. Britain 139/78 1,282,193 11/1961 France ..-l39/78 760,419 10/ 1956 Great Britain 1 39/55 Primary Examiner-lanes Kee Chi Attorney-Walter Becker [57] ABSTRACT Dobby having cams of a varying ratio for looms, in combination comprising a rotary cam carrying drum, interchangeably carrying a plurality of cams, each of which through a cam follower means and a suitable spring return lever system operating a corresponding heddle carrying frame in the loom. The cams may be either disc cams or chain cams at the same time winding up on a second idle drum which can be moved to or away from the first drumto accomodate chain learns of a different length for operating ,said chain cams.

2 Claims, 3 Drawing Figures PATENTEDuma I972 SHEET 1 OF 2 INV EN TOR PATENTEDum m2 I I 3,695,304

- SHEET 2 0F 2' This invention relates to a dobby mechanism having cams of a varying ratio and more particularly a fast dobby wherein the several cams independent of one another controlling the movements of the heddle carrying frames in a loom may be, depending on the particular ratio to be provided, indifferently disc cams and/or chain cams, readily replaceably by other disc and/or chain cams of different profile and length to accomodate the pattern requirements on the fabric being formed.

Dobbies with disc cams and dobbies with battens or strips of wood are already known, each of which having both advantages and disadvantages; particularly, in known cam dobbies, if any cam may be independent of the other cams, howeverthe ratio thereof is limited, since large-sized disc cams cannot be provided for obviousoverall size reasons and driving problems. Other wise, batten dobbies have an unlimited ratio, thereby it being however necessary to set for repeating the cloth back weaves even when itwould be unnecessary due to the smallratio thereof. I i I The object of the present invention is to provide a fast operating cam dobby'ha'ving the advantages of the above cited known dobbies, but overcoming the disadvantages thereof.

Therefore, the dobby according to the invention will be characterized by a varying ratio on each individual heddle, the individual cams being independent of one another and comprising disc cams for low ratios and chain cams of a varying length for higher ratios.

Substantially, the dobby according to the present invention comprises in combination a cam carrying drum for carrying a plurality of cams independent of one another, such cams being of a disc and/or chain type, at least a second idle drum for the chain cams, and follower means resiliently operated for movement control of the heddle carrying frames in a loom to which the dobby is applied, wherein said idle drum can be placed and fixed at an adjustable distance relative to the cam carrying drum depending on the length of the chain cams being used.

Therefore, by the dobby according to the present invention the ratio of a cam can be varied independently of that of the remaining cams.

In order that the invention be better understood, reference is made to the appended drawings showing by mere way of example a preferred embodiment. In the drawings:

FIG. 1 is a vertical longitudinal section of the dobby according to line 1-l of FIG. 2;

FIG. 2 is a sectional view ac'cording'to line 2-2 of FIG. 1; and I FIG. 3 is a fragmentary sectional view substantially according to line 3--3 of FIG. 2.

Referring to the drawings, it will be seen that the dobby substantially comprises a cam carrying drum 1 The cams are independent of one another and may comprise disc cams an driving wheels, indicated at 7 in FIG. 3, or chain cams, indicated as a whole at 8 in FIG. 1

Each of the chain cams 8 comprises a plurality of links 9 pivoted to one another and suitably shaped to provide the cam with the desired contour to achieve the pattern repetition on the fabric with a predetermined or any ratio. Each of the chain cams 8 is driven by a driving ring or wheel 10 carried by drum 1 and provided with seatings or notches 11 (FIG. '1) along its periphery, engaging corresponding projecting elements 12 in each link of the chain cam; if desired, the position of seatings 11 and projections 12 could also be inverted. A suitable idle drum 13, provided with a corresponding driving ring 14, is for supporting the chain cam 8 at its other end. The driving rings or wheels 10 and/or the disc cams 7 are threaded on drum 1 and secured thereto between said end flange l' at one end and a stop ring 1" at the other end. Suitable through holes in the driving rings 10, disc cams 7 and stop ring allow the passage of bolts 15 screwing down in corresponding threaded holes in flange l Since each of the chain cams 8 may be of a varying length, in order to vary the repetitive pattern ratio, said idle drum 13 (FIG. 1) is slidably carried in longitudinal guides 16 (only one of which shown by dashed lines in FIG. 1), which guides are located on the side walls of case 6 and by which the idle drum 13 can be moved to or away from the cam carrying druml. A suitable tension means 17 provides for securing the idle drum 13 at its correct position, imparting the desired tension to the chain cams 8.

In the dobby each of the cams are provided with a proper lever mechanism to operate the corresponding heddle, schematically shown and indicated at 27 in FIG. 1. To this end, there is for each cam a first lever 18 pivoted at an intermediate location 19 thereof and having a first arm with cam follower 20 constantly maintained adhering to the cam contour associated therewith, and a second arm pivoted at one end of a connecting rod 21, the other end of which is pivoted to an intermediate location of a second lever 22 pivoted at one end 23 thereof. The other end of lever 22 is pivoted to one end of a further connecting rod 24 which, in turn, is pivoted by its other end to a vertical rod 25 emerging from the dobby case 6 and connecting by a fastener 28 to the-corresponding overlying heddle schematically shown in FIG. I. Said second arm of the first lever 18 is also connected to a resilient return means; more particularly, said second arm is pivoted at 29 to a plate 30, to which the upper ends of helical springs 26 are hooked, the lower ends of said springs 26 being hooked at corresponding holes of fixed block 31 within the case 6.

Thus, said helical springs 26 constantly maintain the cam follower 20 in contact with the contour of the as sociated cam. From the foregoing it is apparent that the lever system associated with each cam will be substantially identical, except for lever 22, the length of which varies depending on the position of the heddle associated therewith, as shown for lever 22 depicted by dashed lines in FIG. 1.

From the foregoing and as shown in the appended drawings, it should also be understood that a dobby is provided of an extremely simple construction, capable of carrying out any desired ratio; as known, in a fabric not all of the warp yarns making up the weave follow the same path. Thus, there are the back threads which, inthis case, are operated by the disc cams, whereas the weft yarns, having a higher and uneven weft ratio, are driven by the above specified type of chain earns, the composable contour links of which substantially provide for no limits as to the chain length and hence the weft shed.

The above matter, as described and shown in the appended drawings, was given only by way of example, it being understood that other changes may be made without departing for this from the covering field of the invention.

What is claimed is:

l. A dobby having cams of a varying ratio for looms having heddles and operable at high working speeds, in combination comprising a case, a rotary cam carrying drum in said case and adapted for interchangeably carrying a plurality of independent chain cam driving wheels replaceable with disc cams according to number of repetitions of pattern to be obtained, chain cams driven by said chain cam driving wheels, an idle drum for the rotating chain cams parallel to and spaced apart from said first-mentioned drum, and cam follower means subjected to resilient return means and operatively connected with a lever system for controlling the movement for the heddles of the loom, said dobby also comprising guide means for said idle drum and tension means operating on the latter for positioning at the desired position along said guide means adjusting the tension in said chain cams, each of the chain cams comprising a plurality of composable profile links having rises and dwells corresponding in height to those of said disc cams, said links being pivoted with each other and defining a continuous profile of the chain itself to provide a continuously engaging surface supporting said cam follower means with length thereof depending on the determined waft ratio.

2. A dobby in combination according to claim 1, wherein said resilient return means and lever system for independently controlling the movement for the heddles comprise a first lever pivoted at an intermediate location thereof and provide with said first arm having a cam follower means and a second arm connected by a connecting rod to a second lever pivoted at one end thereof, the other end of said second lever being connected by a further connecting rod to a control rod of the associated heddle, said first lever being further pivoted to an anchoring plate of one end of helical return springs of said return means, the other end of which is connected to a block fixed to said case. 

1. A dobby having cams of a varying ratio for looms having heddles and operable at high working speeds, in combination comprising a case, a rotary cam carrying drum in said case and adapted for interchangeably carrying a plurality of independent chain cam driving wheels replaceable with disc cams according to number of repetitions of pattern to be obtained, chain cams driven by said chain cam driving wheels, an idle drum for the rotating chain cams parallel to and spaced apart from said firstmentioned drum, and cam follower means subjected to resilient return means and operatively connected with a lever system for controlling the movement for the heddles of the loom, said dobby also comprising guide means for said idle drum and tension means operating on the latter for positioning at the desired position along said guide means adjusting the tension in said chain cams, each of the chain cams comprising a plurality of composable profile links having rises and dwells corresponding in height to those of said disc cams, said links being pivoted with each other and defining a continuous profile of the chain itself to provide a continuously engaging surface supporting said cam follower means with length thereof depending on the determined waft ratio.
 2. A dobby in combination according to claim 1, wherein said resilient return means and lever system for independently controlling the movement for the heddles comprise a first lever pivoted at an intermediate location thereof and provide with said first arm having a cam follower means and a second arm connected by a connecting rod to a second lever pivoted at one end thereof, the other end of said second lever being connected by a further connecting rod to a control rod of the associated heddle, said first lever being further pivoted to an anchoring plate of one end of helical return springs of said return means, the other end of which is connected to a block fixed to said case. 